On a diesel engine, it is known that high drive forces must be applied to the crankshaft of the fuel injection pump. These forces are significantly greater when large modern diesel engines are fitted to industrial vehicles. However, it is essential to introduce a variable angular displacement into the drive transmission of the injection pump shaft, this variation having to take into account the momentary operating conditions of the engine in order to carry out the control of the injection advance.
Mechanical automatic devices for controlling the injection advance are known. These devices do not stand up well to high drive forces and therefore are falling out of use in the case of large diesel engines.
Several types of hydraulic automatic devices for controlling the injection advance are known, and these do not have the disadvantage of the mechanical devices. The hydraulic devices are generally found in the form of a coupling sleeve, and are in all cases bulky and complicated. These devices are more costly in that they complicate the fitting of the injection pump.